Magnetic storage matrix capable of storing fixed words



N v- 29, 96 A. M. SCHULTE ETAL 3,289,177

MAGNETIC STORAGE MATRIX CAPABLE OF STORING FIXED WORDS Filed May 8. 1962 INVENTORS ANTHONIUS M. SCHULTE JOHANNES STEENBERG W If AGENT United States Patent 3,289,177 MAGNETIC STORAGE MATRIX CAPABLE OF STORING FIXED WORDS Anthonius Maria Schulte, Delden, and Johannes Steenberg, Enschede, Netherlands, assignors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed May 8, 1962, Ser. No. 193,249 Claims priority, application Netherlands, May 10, 1961, 264,643 2 Claims. (Cl. 340 174 The invention relates to a magnetic storage matrix provided with a number of cores consisting of magnetisable material having a large remanence. The matrix is also provided with at least two sets of electrical conductors arranged so that a field can be set up in each of said cores by a current in a certain conductor belonging to a certain one of the sets of conductors and also by a current in a certain conductor belonging to said second set of conductors mentioned above. At least part of the cores can be made inoperative as storage means by providing a core which must be inoperative with a low resistance path for electric currents, which path encloses said core.

Storage matrixes of this type are applied in data processing systems, such as electronic computers or electronic control systems for the purpose of supplying a number of fixed combinations of bits. The supply of a certain combination or word is initiated by causing a current to flow through a certain conductor, belonging, for example, to the first set of conductors. Voltages will only be induced in such conductors of a second set of conductors which enclose the field set up by the selected conductor from the first set in a core which has not been made inoperative. A core which has been made inoperative does not induce a perceptible voltage. The manufacture of special matrixes for special combinations of fixed words is rendered superfluous by this construction. It permits any given combination of fixed words to be produced by a standard storage matrix which has not been especially wound for this combination and which, consequently, is far less expensive than a matrix which has been especially wound. Furthermore, the number of errors in a standard matrix will.be less than in a specially wound matrix.

In a known embodiment of such a matrix, the complete matrix is embedded in a flat plastic plate, with the exception of the ring shaped cores each of which is in a cylin drical opening of the said flat plate. The plate is mounted in a horizontal position and its lower side is covered by a rigid punched card possessing a punching below each opening in which a core is present which must be made inoperative for the combination of words for which the card is valid. Underneath the punched card an elastic container filled with mercury is mounted. This container is distorted in such a way and to such an extent that the mercuy enters those openings containing cores underneath which a punching in the card is present without, however, reaching the upper side of the plastic plate. The mercury acts as a short circuited winding for every core situated in an opening to which the mercury has obtained access through a punching in the card. Consequently, the cores situated in the openings underneath which the punching in the card is present are made inoperative. This known method has various disadvantages. It is necessary for the matrix to be mounted horizontally, although, as a rule, the various cards carrying parts of the circuit of a data handling system are mounted vertically. Furthermore, the horizontal mounting must be effected very accurately, in order to prevent certain openings from overflowing at the top side of the plate, thus permitting the mercury to enter openings which it should not enter, while on the other hand certain openings which should contain mercury will not receive enough of this fluid to form a short circuited path for the cores in the said openings. Also this matrix is unsuitable for transportable data handling apparatus. In fact, it even must be very rigidly mounted so that vibrations of its mounting will not cause the mercury to leave certain openings at the upper side of the plate, as a result of which it might enter openings which should not contain mercury. Furthermore, it may be necessary to provide suitable gaskets and means for pressing the punched card against the plate, or to glue the card to the underside of the plate in order to prevent leakage of the mercury into openings which should not contain mercury. In addition, special measures must be taken in order to prevent drops of mercury from leaving the matrix system and causing short circuits in other circuitry of the data handling system.

The invention avoids all these disadvantages. According to the invention, the matrix is built in such a way that a winding with a low resistance enclosing a core consists of an electrically conductive layer which encloses the core and covers it at least partly. Perfera-bly, such a layer consists of an electrically conductive paint.

A matrix according to the invention can be mounted in any desired position in the frame of the data handling system. No special measures need be taken in order to prevent leakage of a fluid because the matrix according to the invention does not contain any fluid.

The invention will now be described with reference to the figure, which shows a part of a standard storage matrix to which the invention can be applied.

The figure shows a part of a storage matrix with ring shaped magnetic cores. This part comprises 9 magnetic cores. The ring-shaped cores, such as 1 and 2, are shown perpendicular to their axes, so that they are represented by rectangles. The core material shows a substantial remanence so that its hysteresis loop is more or less rectangular. Each ring-shaped core is arranged so as to form part of a column running from the top of the drawing downwards and of a line running from left to right on the drawing. In the embodiment shown in the figure, the columns and lines are straight and mutually perpendicular. The magnetization of a core-has a certain direction if the core stores a bit of a certain type, e.g., a .1 :bit, and the opposite direction if it stores a bit of the other type, such as a 0 bit. Three sets of conductors are provided in this embodiment for the purpose of exciting the cores. Each conductor of the first set, such as the conductors 3 and 4, runs from the top downwards passing through the rings of a column of cores. Each of the conductors of the second set, such as the conductor 5, runs from left to right, passing through the cores on the same line. There is also a third conductor passing through all the rings of the complete storage matrix. This conductor is shown in the figure as a set of conductors such as 6, each of which passes through the rings of a line. All of these conductors are connected in series. It is, however, not necessary for the conductor of the third set to have the same direction as the conductors of one of the other sets. It suflices if conductors connected in series are present which pass in the same direction through all cores of the matrix. These conductors may have a direction which is oblique with to the directions of the conductors of the other sets. The operation of such a matrix is well known in the art and needs little elucidation. A current with a strength i passes through the conductors of the third set, such as 6. This current supplies i ampere-turns for each core and is not strong enough to exert a perceptible influence on the magnetization of the cores with a large remanence through which these conductors pass. The field strength remains within the part of the magnetization curve in which only a very small change in magnetization occurs.

The various bits of a word or sign are stored by the various cores of a single line. During an operation, generally called writing, the magnetization of each core in a line in which a word is to be stored is given a direction corresponding to the character of the bit to be stored by it. During this writing operation only a field with a certain direction can be set up in the cores, so that the writing currents are only able to magnet-ize the cores in a. direction corresponding to a certain type of bit. Magnetization corresponding to the other type of bit must result from the absence of a sufficiently strong writing field during the writing operation. Consequently, prior to the writing operation, all the cores of the line must be magnetized in the direction opposite to that of the writing field. This is etfected during the reading operation, as will be shown below. During this operation the cores of a line are magnetized in a direction corresponding to the direction of the field set up by the current with the strength i in the conductors of the third set. If a word is to be written on the upper line of the matrix shown in the figure, a current with a strength 2i and a direction opposite to the direction of the constant current in the conductor 6 is caused to flow through the conductor 5. Because the fields set up by the currents in the conductors 5 and 6 have opposite directions still, no more than i ampere-turns are available for the cores on the said line. If, during the writing operation, the magnetization of the core 7 must obtain a direction which is opposite to that resulting from the reading operation, a current with a strength which is also 21 and in such a direction that its field supports the field set up by the current in the conductor 5 is caused to flow through the conductor 3. Then 3i ampere-turns are available for magnetizing the ring core 7, which is sufiicient to reverse the magnetization of this core. Magnetization in this direction indicates that the said core stores a 1 bit.

If the word stored by the said line is to be read, then a reading current with a strength 21' and such a direction that its field has the same direction as the field set up by the current in the conductor 6 is caused to flow through the conductor 5. In this case 3i ampere-turns also are available for the cores of the upper line. The direction, however, is opposite to the direction of the field which elfected the writing operation. If the direction of magnetization of a core has not been reversed during the writing operation, the reading current in the conductor 5 has no eflect. It the direction of magnetization of a core has been reversed during the writing operation, this direction is again reversed. In the absence of special measures, this reversal of the magnetization induces a voltage pulse in a conductor, such as 3, which passes through the said ring core from the top downwards, and this voltage pulse indicates that a 1 bit has been read.

According to the invention, the standard matrix described above can be used to obtain a fixed registration for a given word. In this case, if the occurrence of a pulse in a read wire is to be prevented, an electric circuit with a low resistance is provided, which encloses the field in said core. This circuit does not prevent the direction of magnetization from being reversed by the reading current, but this reversal causes a relatively strong current to flow in the low resistance circuit. As a result of the self inductance of this circuit, current flow is maintained for a relatively long interval. According to the induction law this current opposes the field change causing it. Consequently, the reversal of the magnetic field in a ring 7 enclosed by a conductor 3 will progress at a substantially slower rate than it would in the absence of the said circuit with low resistance enclosing the core. The voltage induced in the conductor 3 is proportional to the rate of change of the field in the core, so that it will be much lower when a short circuited winding is present on the core than when no such winding is present. The presence of a short circuited winding on a core causes such a reduction in the amplitude of the pulse induced in the conductor 3 that, by very simple means, such as a simple threshold circuit, the system cooperating with the matrix can be made insensitive to the pulses supplied by a core with a short circuited winding. Such short circuited windings on certain cores adapt a matrix storage to the task of supplying a number of fixed words. Each of these words is stored on a line of the matrix by providing the cores which are not to supply voltage pulses for the said Word with such a short circuited winding. If one of the fixed words is to be supplied, this supply is prepared by causing all the cores of the line of the matrix on which this word is stored by means of short circuited windings to be magnetized in the direction corresponding to a 1 bit by currents with a strength 2i in the conductors for all the columns as well as in the horizontal conductor 5 for the said line. If desired, all the cores of the matrix may, for this purpose, be magnetized in the said direct-ion by currents in all the horizontal and in all the vertical conductors of this matrix. Then if the word stored in a certain line by means of short-circuited windings on certain cores of this line is to be supplied, this is initated by causing a reading current to flow in the horizontal conductor, such as 5, of the said line. This current, together with the current in the conductor 6, causes the magnetization of all the cores of the said line to be reversed. This reversal will induce sufficiently strong pulses only in those vertical conductors enclosed by ring cores on the said line which do not carry short circuited windings.

In the magnetic storage matrix according to the invention, the winding with low electrical resistance which renders a core inoperative consists of an electrically conductive layer on the core, e.g., a layer of electrically conductive paint or the like. In the figure, cores 1 and 2 are each supplied with an electrically conductive layer, indicated by the reference numerals 9 and 8, respectively. It is not necessary that this layer cover the core completely and in applying the layer only a few precautions need be exercised. The core may be covered with the electrically conductive paint by means of a small brush. In doing so, care should be taken that the covering enclose the field in the core. Therefore, at least part of the inner side of the core must be covered with paint. Paints containing small metal particles can be used. Very good results have been obtained with a paint containing silver grains. It is important to use a paint which can be easily removed by means of a solvent. Settings can then be changed, if necessary. It must be admitted that effecting a change in this way takes a considerable amount of time, for the paint must be carefully and pretty well completely removed without damaging the thin wires and the cores. The matrix according to the invention is, however, intended to be used in cases in which the setting is never, or rarely changed. The low price of this matrix is, however, its important advantage. The matrix of the type described in the preamble permits easier changes of its setting, but this advantage is dearly paid for. On the other hand, the present invention can be applied to nearly any standard matrix on the market. In order to set a certain pattern of fixed words into such a standard matrix, it is only necessary to cover certain cores with a layer of conductive paint. Suitable types of conductive paint are well known. It is also obvious that a matrix according to the invention 1s less expensive than amatrix storage of the well known type in which fixed settings are effected by means of small permanent magnets.

It is obvious that it is by no means necessary for a matrix to possess three sets of conductors in order to be able to effect the operations described above. Moreover, it is not necessary for the magnetization of the cores to be effected by currents in conductors belonging to more than one set of conductors. The construction described has been selected because standard storage matrixes as a rule possess three sets of wires, and because if three sets of wires are used, the circuit cooperating with the matrix can be of a standard type as used in combination with matrix storages used for storing variable signal or words. If, moreover, in a matrix having three sets of wires, and which is used for storing fixed words, certain lines are not used for this purpose, these latter lines may be used for storing variable words, which in this case can be read and written by the same standard reading and writing circuit used for reading the fixed words. If a matrix is used only for supplying fixed words, and if it is desirable for this matrix to be as simple as possible, then two sets of conductors are sufficient. In this case one of these sets may be the set, which, in the drawing, runs from the top downwards, and is used for supplying the pulses generated in these wires by the changes in the magnetization of cores enclosed by these wires. The second set of wires may be one of the sets, which, in the drawing, runs from left to right. If such a matrix storage is to supply a certain signal, a current is first caused to flow through the horizontal wire belonging to the line on which the said signal has been permanently set. The strength and the direction of this current are such that the cores on this line are magnetized to such an extent and in such a direction that a reversal of the magnetization induces a pulse with the required strength and polarity in a vertical conductor enclosing such a core. The eventual supply of the signal is initiated by a current in the said horizontal wire with the same strength but the opposite direction. This current causes the magnetization of all the cores on the line to be reversed. As has been described above, pulses will be induced only in those vertical wires which enclose the field of a core on the said line which does not carry a short circuited winding. In such a matrix it is superfluous for the vertical wires, such as 3 and 4, to carry any current for the purpose of preparing the storage matrix for supplying one of its fixed words.

What we claim is:

1. A magnetic storage matrix comprising a plurality of magnetic cores, each of said cores being composed of a magnetic material having a large remanence and a substantially rectangular hysteresis loop, a first set of electrical conductors and a second set of electrical conductors, each of said cores being inductively coupled with a conductor of said first set of conductors and with a conductor of said second set of conductors, and means for effectively disabling selected ones of said cores comprising a short circuit path for electric current encircling said selected ones of said cores, said short circuit path comprising a layer of electrically conductive paint on each of said selected cores and covering at least a portion of said cores.

2. A magnetic storage matrix comprising a plurality of magnetic cores each of which is composed of a magnetic material having a large remanence, a first and second set of electrical conductors threading said cores, each of said cores enclosing a conductor of said first set of conductors and a conductor of said second set of conductors, and means providing a low resistance path for electric current enclosing selected ones of said cores, said low resistance path means comprising a layer of electrically conductive paint applied to and covering at least a portion of said core.

References Cited by the Examiner UNITED STATES PATENTS 3,038,147 6/1962 Grenchus 340-174 3,092,812 6/1963 Rossing et al 340-l74 3,130,391 4/1964 Merz 340-174 BERNARD KONICK, Primary Examiner.

IRVING SRAGOW, Examiner.

H. D. VOLK, J. W. MOFFITT, Assistant Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,289,177 November 29, 1966 Anthonius Maria Schulte et al.

at error appears in the above numbered pat- It is hereby certified th said Letters Patent should read as ent requiring correction and that the corrected below.

line 60, after "with" insert respect Column 2,

strike out "still".

column 3, line 23,

Signed and sealed this 19th day of September 1967 L) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents 

1. A MAGNETIC STORAGE MATRIX COMPRISING A PLURALITY OF MAGNETIC CORES, EACH OF SAID CORES BEING COMPOSED OF A MAGNETIC MATERIAL HAVING A LARGE REMANANCE AND A SUBSTANTIALLY RECTANGULAR HYSTERESIS LOOP, A FIRST SET OF ELECTRICAL CONDUCTORS AND A SECOND SET OF ELECTRICAL CONDUCTORS, EACH OF SAID CORES BEING INDUCTIVELY COUPLED WITH A CONDUCTOR OF SAID FIRST SET OF CONDUCTORS AND WITH A CONDUCTOR OF SAID SECOND SET OF CONDUCTORS, AND MEANS FOR EFFECTIVELY DISABLING SELECTED ONES OF SAID CORES COMPRISING A SHORT CIRCUIT PATH FOR ELECTRIC CURRENT ENCIRCLING SAID SELECTED ONES OF SAID CORES, SAID SHORT CIRCUIT PATH COMPRISING A LAYER OF ELECTRICALLY CONDUCTIVE PAINT ON EACH OF SAID SELECTED CORES AND COVERING AT LEAST A PORTION OF SAID CORES. 